1. Field of the Invention
This invention generally relates to connecting optical fibers, and more particularly to a fiber-optic cable and cable connector equipped with a circuit for verifying that an optical connection has been established. The invention is also a method for making a connector of this type.
2. Description of the Related Art
In order to ensure that an optical system will operate reliably, it is important to confirm that its optical connectors are properly installed. One proposed approach which addresses this problem involves attaching an electrical wire to an external portion of an optical fiber. In operation, this wire carries electrical signals from a connector attached to one end of the fiber to a connector attached to a second end of the fiber. When the signals are received by the second connector, it is determined that a valid, optical connection exists. In systems of this type, the connectors are usually plug-type connectors which are adapted to interface to a controller of a network management system.
The proposed approach described above has proven to have several drawbacks. First, the electrical wires consume space within the connector, and their attachment to the fiber increases the fiber size. This undermines attempts at miniaturization and increases the overall cost of the system. Also, because the electrical wires are externally attached to the fiber, they are susceptible to damage, which compromises the reliability of the system.
In view of the foregoing considerations, it is apparent that there is a need for a fiber-optic cable connector which uses an improved circuit for confirming that an optical connection has been established, and moreover one which consumes less space and is more affordable to implement than conventional approaches.
In one preferred embodiment of the present invention a fiber-optic cable and cable connector is provided which contain a verification circuit that is more affordable, consumes less space, and is more efficient than conventional circuits used to perform this function.
In another aspect of the present invention, a verification circuit is at least partially integrated within the internal structure of an optical fiber.
In another preferred embodiment of the present invention, a verification circuit is provided as described above which is equipped with or is connected to an electronic device which informs a user that a proper optical connection has or has not been established.
The foregoing are achieved by providing a fiber-optic cable which includes a conductive coating formed on an optical fiber. The conductive coating may be in the shape of a band or ring located at a terminal end of the fiber, or may extend along the entire length of the fiber or a portion thereof. For protection purposes, the fiber is covered with a buffer made, for example, from a plastic or polymer. Through this conductive coating, connection of the optical fiber to either another fiber or to an opto-electronic device may at all times be confirmed.
The fiber-optic cable connector of the present invention includes a receptacle and plug, the latter of which is preferably connected to the terminal end of the fiber-optic cable of the invention. The receptacle is equipped with a verification circuit which confirms that the optical fiber in the plug has established an optical connection with the receptacle. The verification circuit includes a contact element at a location which coincides with a position of the conductive coating when the plug is inserted into the receptacle. When the conductive coating and contact element touch, an electronic device connected to the contact element provides a user with an indication that an optical connection has been made. If an optical connection is not made, the electronic device provides an indication of the same. The electronic device may be a light-emitting diode or audible alarm. In an alternative embodiment, the fiber-optic cable of the present invention may be incorporated into the receptacle of the connector. In this case, the verification circuit would be formed in the plug.
The power source for the alarm may be a battery incorporated into the receptacle housing or may derive from an electronic device to which the plug is connected. In addition to providing an indication that an optical connection has been made, the conductive coating may operate as a transmission line for carrying electrical signals, which may be analog or digital. Also, the invention is ideally suited for verifying optical connections between cables that contain fiber-optic bundles.